18199809 has 20 divisors (see below), whose sum is σ = 28788804. Its totient is φ = 11418624.

The previous prime is 18199801. The next prime is 18199823. The reversal of 18199809 is 90899181.

It can be written as a sum of positive squares in 2 ways, for example, as 10909809 + 7290000 = 3303^2 + 2700^2 .

It is not a de Polignac number, because 18199809 - 2³ = 18199801 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18199801) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 5232 + ... + 7985.

Almost surely, 2^18199809 is an apocalyptic number.

It is an amenable number.

18199809 is a deficient number, since it is larger than the sum of its proper divisors (10588995).

18199809 is a wasteful number, since it uses less digits than its factorization.

18199809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13246 (or 13237 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 45.

The square root of 18199809 is about 4266.1234159363. The cubic root of 18199809 is about 263.0402912629.

It can be divided in two parts, 1819 and 9809, that added together give a triangular number (11628 = T₁₅₂).

The spelling of 18199809 in words is "eighteen million, one hundred ninety-nine thousand, eight hundred nine".